The present invention relates to a process for the production of sensitive plates for exoelectron dosimeters.
Exoelectrons detectors are now well known. It is known that a plate made from certain crystalline materials has its electrons transferred from the valence band to the conduction band of the crystal lattice when it is subject to irradiation. A certain proportion of these electrons are captured in traps of the crystal lattice. These traps are either due to impurities of the crystal or to faults in the crystal lattice. In order to free the electrons from these traps, energy must be supplied to the crystal lattice. This energy supply process, called stimulation can have an optical or a thermal origin. By measuring the quantity of electrons which are freed in this way and which are hereinafter called exoelectrons, it is possible to deduce the irradiation dose previously absorbed by the sample. The electrons freed by the crystal during stimulation are detected and measured by an exoelectron reader during the stimulated exoelectron emission phenomenon. For example, this emission of exoelectrons is measured by means of a gas circulation Geiger-Muller counter or by a windowless electron multiplier.
In the French Patent Application filed on Sept. 17, 1976, by the Commissariat a l'Energie Atomique for "Materials for producing exoelectron detectors" materials are described which are particularly suitable for forming the sensitive plate of an apparatus for dosing radiation by exoelectron emission, said apparatus being conventionally called a dosimeter.
In the above-mentioned French patent application, which forms an integral part of the present description, the fact that the material for making the sensitive plate of the device for measuring the radiation by exoelectron emission is characterised in that it comprises a first member having traps for the electrons and which can emit exoelectrons by thermal or optical stimulation and a second member having a good ionic conductivity and able to give a solid material is described and claimed. Preferably, the second substance is made from alumina crystallised in the .beta. phase, preferably the first substance is selected from the first group comprising .alpha. alumina and beryllium oxide. However, the first body may also be chosen from the group comprising CaSO.sub.4 ; BaSO.sub.4 ; FCa.sub.2 ; SrSO.sub.4 and LiF.
The sensitive plate of the dosimeter is in fact constituted by the deposit of a substance or more specifically the mixture of the substances defined hereinbefore on a support.